Fluorescent lamps are well known and are used as a light source for various types of office automation equipment as well as for general lighting purposes and as a backlighting source for liquid crystal display units. Recently, there has been demands for miniaturization or increased effective luminescent length of these light sources. Due to limitations in space available for various applications, it is desired to reduce the size of the lamp or increase the effective luminescent length when the length of the lamp is not changed.
Conventionally, in low pressure discharge lamps of this type, that is, straight fluorescent lamps for example, the bi-pin type bases, which each have a couple of terminal pins extending in the axial direction of the bulb, are used as the bases attached to the ends of the bulb. Since the bases each have a couple of terminal pins protruding in the axial direction of the bulb, the entire length including the terminal pins is long. In addition, lamp sockets need to provide for the axial ends of the lamps in a manner that the lamp sockets are placed against the bases. As a result, the whole lighting equipment including the lamp sockets has to be large.
European Patent Application No. 0 281 079 discloses a low pressure discharge lamp having a pair of bases attached to opposite ends. Each base has a cylindrical base body into which the end of the bulb is inserted. The base is firmly secured to the bulb by an adhesive supplied between the end of the bulb and the inner surface of the base body. A pair of receiving terminals protrude from the base body in a direction perpendicular to the axis of the bulb.
U.S. Pat. No. 4,906,891 which issued to Takagi et al on Mar. 6, 1990, discloses a low pressure discharge lamp having a pair of bases fastened to the end of the bulb by injecting an adhesive into the gap between the bulb and the bottom wall of the base body. Each base member has a pair of terminals containing contact portions which project from the periphery of the base body and include contact surfaces extending parallel to the axis of the bulb and facing the same direction. The contact surfaces are located so as to contact a common plane.
Although the above-described lamp bases have been employed with varying degrees of success, it has been found that certain disadvantages do exist and such bases do leave something to be desired. More specifically, it has been found that such bases of the prior art require the use of an adhesive or the like to fasten the base to the lamp bulb. Moreover, some of the base/socket arrangements disclosed by the prior art do not accommodate for differences in the overall length of the lamp and/or leave a portion of the base terminals exposed when inserted in a socket and therefore may present a shock hazard.